glucose tolerance test


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glu·cose tol·er·ance test (GTT),

a test for diabetes, or for hypoglycemic states such as may be seen, rarely, in patients with insulinomas. Following ingestion of 75-g glucose while the patient is fasting, the blood sugar promptly rises and then falls to normal within 2 hours; in diabetic patients, the increase is greater and the return to normal unusually prolonged; in hypoglycemic patients, depressed glucose levels may be observed in 3-, 4-, or 5-hour measurements.

glucose tolerance test (GTT)

a test of the body's ability to metabolize carbohydrates by administering a standard dose of glucose and measuring the blood and urine for glucose level at regular intervals thereafter. The patient usually eats a high-carbohydrate diet for the 3 days before the test and fasts the night before. A fasting blood glucose level is obtained the next morning, and then the patient drinks a dose of glucose based on his or her weight. Blood and urine are collected periodically for up to 6 hours. The glucose tolerance test is most often used to assist in the diagnosis of diabetes, hypoglycemia, or other disorders that affect carbohydrate metabolism.

glucose tolerance test

A standardized test that measures the body's response to an oral–challenge dose of glucose, which is primarily used to confirm the diagnosis of DM, and may be performed in individuals with symptoms–eg ↑ fasting glucose level, hypertriglycerdemia, neuropathy, impotence, glycosuria that are suggestive of DM; in pregnancy GTT is used to diagnose gestational DM

glu·cose tol·er·ance test

(GTT) (glū'kōs tol'ĕr-ăns test)
A test for diabetes, or for hypoglycemic states such as may be seen rarely in patients with insulinomas. Following ingestion of 75 g of glucose while the patient is fasting, the blood sugar promptly rises and then falls to normal within 2 hours; in diabetic patients, the increase is greater and the return to normal unusually prolonged; in hypoglycemic patients, depressed glucose levels may be observed in 3-, 4-, or 5-hour measurements.

glucose tolerance test

A test of the body's response to a dose of glucose after a period of fasting. The blood sugar levels are measured at various intervals after the sugar is taken and the results plotted on a graph. A characteristic shape of the curve occurs in DIABETES because the blood sugar levels rise to an abnormal height and take longer than usual to return to normal. A urine test also shows sugar, in diabetes.

glu·cose tol·er·ance test

(GTT) (glū'kōs tol'ĕr-ăns test)
Assessment for diabetes or for hypoglycemic states. Following ingestion of 75-g glucose while the patient is fasting, blood sugar promptly rises and then falls to normal within 2 hours; in diabetic patients, increase is greater and return to normal unusually prolonged; in hypoglycemic patients, depressed glucose levels may be observed in 3-, 4-, or 5-hour measurements.

glucose, d-glucose

a simple sugar, a monosaccharide in certain foodstuffs, especially fruit, and in normal blood; the major source of energy for many living organisms. See also dextrose.
Glucose, whose molecular formula is C6H12O6, is the end product of carbohydrate digestion; other monosaccharides (fructose and galactose) are largely converted into glucose. Glucose is the only monosaccharide present in significant amounts in the body fluids. The oxidation of glucose produces energy for the body cells; the rate of metabolism is controlled by a number of hormones the most important of which are insulin and glucagon. Glucose that is not needed for energy is stored in the form of glycogen as a source of potential energy, readily available when needed. Most of the glycogen is stored in the liver and muscle cells. When these and other body cells are saturated with glycogen, the excess glucose is converted into fat and stored as adipose tissue. See also hypoglycemia, hyperglycemia.

[1-14C]-glucose
radioactive glucose used experimentally.
liquid glucose
a thick syrupy, sweet liquid, consisting chiefly of dextrose, with dextrins, maltose and water, obtained by incomplete hydrolysis of starch; used as a flavoring agent, as a food, and in the treatment of dehydration.
glucose-1-phosphate
an intermediate in carbohydrate metabolism.
glucose-6-phosphatase
a liver (and kidney) enzyme that irreversibly cleaves glucose-6-phosphate to free glucose and phosphate; important in glucose homeostasis.
glucose-6-phosphate
an intermediate in carbohydrate metabolism.
glucose-6-phosphate dehydrogenase (G6PD)
a regulatory enzyme in the metabolism of glucose-6-phosphate. A deficiency of the enzyme in the erythrocyte results in a hemolytic anemia; an inherited abnormality in humans, rats and mice and acquired in animals in phenothiazine toxicity and ingestion of kale.
glucose phosphate isomerase
converts glucose-6-phosphate to fructose-6-phosphate and the reverse reaction.
glucose suppression test
suppression of blood levels of growth hormone by the intravenous administration of glucose is used to diagnose acromegaly.
glucose tolerance factor (GTF)
a naturally occurring substance containing chromium which potentiates the effects of insulin.
glucose tolerance test
a test of the body's ability to utilize carbohydrates. It is often used to detect abnormalities of carbohydrate metabolism such as occur in diabetes mellitus, hypoglycemia, and liver and adrenocortical dysfunction. If administered orally, it may also be used to assess the absorptive capacity of the small intestine.
References in periodicals archive ?
O'Sullivan JB, Mahan CM: Criteria for the oral glucose tolerance test in pregnancy.
8] If there are errors to be made, laboratorians must err in the direction of running too many glucose tolerance tests and diagnosing too many patients with IGT.
The results also raise questions about optimal glucose levels in women with coronary artery disease who undergo a glucose tolerance test, wrote Dr.
It's a big barrier to get them into the system, to get them to the lab to do a formal glucose tolerance test.
He reported on 17,532 individuals who underwent an oral glucose tolerance test as part of the screening process for participation in the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) trial.
In this retrospective cohort study; the researchers analyzed diabetes risk over a mean 9-year follow-up period in 31,000 women without gestational diabetes who had an oral glucose tolerance test (OGTT) or oral glucose challenge test (OGCT) during their pregnancy.
The data from Kaiser Permanente of Colorado include all 36,403 pregnancies among 30,216 initially nondiabetic women who delivered singleton infants from 1994 to 2002 and had been screened at 24-28 weeks by the same protocol: a 1-hour 50-g oral glucose tolerance test (OGTT), followed by a diagnostic 3-hour 100-g OGTT among those with glucose values at or above 140 mg/dL on the 50-g test.
A woman at low risk of gestational diabetes, based on a negative result from a 1-hour, 50-g glucose tolerance test, will remain at low risk during a subsequent pregnancy within the next 4 years.
Because of their increased risk of developing impaired glucose tolerance and type 2 diabetes, all women with polycystic ovary syndrome should be screened with a 2-hour oral glucose tolerance test, and that test should be repeated every 2 years, according to a statement from the Androgen Excess Society.
Of the 37 mothers who were studied, 10% had diabetes and 26% had impaired glucose tolerance to a 2-hour glucose tolerance test.
8 mmol/L (140 mg/dL) or greater, a formal 75-g oral glucose tolerance test is done.

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